Semi-automatic telephone system



1. WICKS. SEMI-AUTOMATIC TELEPHONE SYSTEM.

APPLICATIION FILED MAR. 21' I918.

Patented June 1, 1920.

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SEMI-AUTOMATIC TELEPHONE SYSTEM.

APPLlCA-TION FILED MAR. 21, 918.

Patented June 1, 1920.

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[Hue 117111" Jul-Ln ZLUKE U1I T E S JOHN WICKS, OF CHICAGO, ILLINOIS, ASS-IGNOR TO AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SEMI-AUTOMATIC TELEPHONE SYSTEM.

Application filed March 21, 1918.

To all whom it may concern:

Be it known that I, JOHN VVIoKs, a citizen of the United States of America, and a resident of Chicago, Cook county, and State of Illinois, have invented certain new and useful Improvements in Semi-Automatic Telephone Systems, of which the following is a specification.

My invention relates in general to that type of telephone systems known as semiautomatic, that is, in which automatic switches are controlled by an operator to establish a connection between a calling and a called subscriber.

My invention is particularly adapted for use in a system in which an operator, when connection is made with a busy subscribers line, may hold said'connection and in which the switch used will automatically. cut

through when the called line is idle.

Among the objects of my invention is to provide means, whereby, when a two way trunk line is held busy another subscriber may come in, select said trunk, release the associated switches'and use the trunk for calling in the other direction.

My invention is particularly valuable in a system in which incoming trunks to a branch exchange terminate in a selector switch which may seize a connector switch in the branch exchange to extend a connection to a subscriber therein, and in which the incoming trunk line is also accessible to calling subscribers in the branch exchange for outgoing calls. In a system of this character the circuits are usually arranged so that when asubscriber is busy to a call from an operator, the connector will stay on the called line until such line becomes idle and then cut through. In a case of this kind it has been found that the incoming trunk line is often held busy to outgoing calls to the main exchange needlessly, as a call might be set up and again released from the branch to the main before the line wanted by the operator in the branch becomes idle. I have therefore provided means, whereby, when such a trunk line is being held by an operator waiting for a called line to become idle, a calling subscriber may seize said trunk line, release the associated switches and call the operator at the main exchange said trunk however being held busy in the usual manner at all other times except when waiting on a busy line. It will be understood that Specification of Letters Patent.

Patented June 1, 1920.

Serial No. 223,685.

the trunk line extending to the jack X is held busy to other operators by the busy signaling lamp 4 which is lighted whenever this trunk is seized either by an operator or by an automatic switch.

ed to be seized either'bythe selector switch E (Fig. 1) or by a local selector (not shown) to extend connections to a called substation similar to that shown at A.

When the operator at the main exchange desires to connect with a subscriber in the branch exchange, the plug of her cord circuit is inserted in the jack X (Fig. 1) and the line relay 2 is controlled by the usual calling. device in the cord circuit. The relay 2 upon energizing, closes a circuit for slow release relay 3 in the usual manner, which relay 3 upon energizing. connects ground to the supervisory lamp 4 through springs 6, and also connects the same ground to the relay 61. Relay 61, upon energizing, connects ground through springs 7 and 8,

and springs 9 and 10 to private contact 5 and its multiples in the banks .of local switches, which are used to seize the trunk to the jack X to extend a call to the main exchange. Relay '61 also disconnects the lead from contact 5 from the upper winding of switching relay 34.- The relay 2 is now operated to send a number of impulses, corresponding to a digit of the called number, to the vertical magnet 11 and relay 12 in series through springs 13 and 14, springs 15, springs 16 and 17, and said relay and magnet to battery. The wipers 18, 19, 20 and 21 are therefore raised by the vertical magnet to a level from which trunk lines lead to the desired group. The slow magnet 26 at springs 28, and closes a looking circuit for itself at springs 29 which passes through springs 30 of the rotary magnet and off normal springs 25. Soon after the line relay 2 comes to rest ener- @gized after the last impulse to the vertimagnet at springs 28. The rotary magnet will now denergize and again close the springs 30. Ifthe first trunk line is busy the private wiper 20 will find ground and a new circuit will be closed for relay 22 from said ground to wiper 20, springs 31', springs 32 and 33, springs 30, springs 25,

and relay 22 to-battery. It will be noted. that the lower winding of relay 34 is also connected in a circuit in series with relay 22 from ground at springs 6, but said relay is at this time short circuited by the ground at wiper20. Relay 22will therefore energize again to close the circuit of magnet 26 and step the wipers to the next set of contacts. This alternate operation of relay 22 and magnet 26 continues until an idle trunk line is reached, at which time no ground will be found by private wiper 20 and therefore relay 34 is no longer shorted out. Relay 34 will therefore energize in series with relay 22, which last relay will not energize due to the hi h resistance of the winding of relay 34. he energization of relay 34 disconnects the line relay 2 from the trunk line from jack X and connects said trunk line to the wipers l8 and 19, and opens a point in the circuit of the release magnet 35 at springs 15. A'further result of the energization of relay 34 is the opening of the previously traced circuit to wiper 20 at springs 32 and 33 and the connection of said wiper through springs 32 and 36, lower winding of relay 34, springs 30, and relay 22 to battery. The relay 3 will remaiIP energized to hold the ground through springs 6 connected to the above circuit 'untll a round is supplied to said holding circuit rom the switch ahead as will be explained.

. As soon asthe relay 34 energizes a circuit is closed for the line relay 37 of the connector switch H (Fig. 2) in series with the above mentioned calling device at the operators cordcircuit. The relay 37 closes a circuit, upon the energizing, for relay 38 from ground through springs 39 and 40. Relay 38, upon energizing, connects ground springs 8 and 7 to the relay 67. Now should through springs 41 and 43 to the release trunk to maintain the switching relay 34 of selector E energized. The line relay operates in response to impulses to close the circuit of vertical magnet 47 in series with slow relay 46 through sprin s 39 and 48, springs 44, and springs 45. agnet 47 operates to raise the wipers 49, 50, and 51 to some level of the connector bank. The relay 46 closes and maintains closed a circuit for private magnet 52 through springs 53 and 54. As soon as the impulses to the vertical magnet cease, relay 46 will deenergize and open the circuit of the private magnet 52 which magnet'allows the side switch wipers 55 and 56 to move to second position. As soon as the wipers 49, 50 and 51 leave normal position the springs 57 and 58 close to prepare certain circuits. The side switch wiper 55 connects battery to rotary magnet 59 and disconnects the same from magnet 47. When the next series of'impulses op' erate line relay 37, said relay opens and closes a circuit for rotary magnet 59 extending from ground through springs 39 and 48, springs 44, springs 45, relay 46, springs 60, and magnet 59 to battery. The wipers 49, 50 and 51 are therefore moved to the contacts leading to substation A, assumed to be the desired substation. Relay 46 again operates to close the circuit of the private magnet 52, and if the called line is busy and a ground is present at wiper 51, the circuit of magnet 52 will not. be broken when relay 46 falls back but will be closed through springs 54 and 62, relay 63, side switch wiper 56 (in second position) andto ground at wiper 51. l have shown the line switch C of the called station operated, assuming that the called line is busy because of some call having been extended therefrom through the medium of line switch C. Relay 63 and -magnet 52 operate over the above circuit,

magnet 52 operating to maintain the side switch in second position, and relay 63 operating to disconnect the rotary magnet at springs 60, connect the busy machine M to the line circuit at springs 64, and also con nects ground through springs 65, through the special wiper 21 and relay 66 of selector E (Fig. 1). .he relay 66 is for the pur ose of rendering the trunk line tothe jack accessible to calling subscribers at this particular time. That is, the operator, upon hearing the busy signal, simply leaves the connection set up and as soon as the called line becomes idle it will cut through. Relay 66 upon energizing, switches the lead from the private contact 5, from the ground on a switch in the branch exchange seize the set of contacts associated with contact 5, no ground will be present thereat and as soon as this seizing switch extends a ground to contact 5, the relay 67 will be energized to open the contact springs 31. The contact springs 31, it will beremeinbered, are in series with the holding circuit of relays 34 and 61, relay 34 will immediately denergize and close a circuit for release magnet 35 at springs 15. As soon as wiper 21 leaves its contact as the switch releases, relay 66 will deenergize and open the circuit of relay 67 which deenergizes after an interval. Relay 66 also closes a circuit from: private contact 5, through springs 10 and 9, springs 8 and 68, and the upper winding of relay 34, which relay 34 then energizes again to disconnect the line relay 2 from the trunk line. The connector switch H also releases as soon as wipers 18 and 19 leave their contacts and thereby open the circuit of line relay 37. The subscriber in the branch who has called may then operate any well known drop or call signal in the operators cord circuit and be connected with the desired line in the main exchange. Assuming that no call was made to the trunk line from the branch exchange then as soon as the called line becomes idle, the circuit for relay 63 and mag net 52 will be opened. Relay 63 removes the busy tone, and causes the relay 66 (Fig. 1) to denergize and again connect the ground from springs 7 and 8 to contact 5. The private magnet 52 allows the side switch wipers and 56 to pass to third position so that ground will be fed through relay 69 and relay 70 and magnet 71 in multiple. Relays 70 and 69 energize over this circuit and cut off the operating magnets of switch C and close contacts 72 and 73. The closure of springs 72 and 73 starts the automatic ringing operation and when the called subscriber responds, this signaling current is disconnected by the operation of relay 74. After relay 74 operates, the relay 75 is operated to reverse the battery to the operator in the usual manner to inform the operator that the called subscriber has answered.

Should a subscriber in the branch exchange call the trunk line to jack X while the said trunk is idle, the ground which the ,calling switch extends to contact 5 will pass through springs 10 and 9, springs 8 and 68, and upper winding of relay 34 to battery. Relay 34 will then operate to disconnect the operating magnets of the selector E, and the drop 76 may be operated to signal the op erator.

It will be seen therefore that I have 'provided very simple and efficient means for accomplishing the results specified.

Having fully described and ascertained my invention, what I consider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims.

What I claim as my invention is:

1. In a telephone system, a two way trunk line,-an automatic switch at one end of said trunk line for extending connection therefrom, means for operating said switch to extend a connection to a busy or idle line and for maintaining such connection if the line is a busy line, another automatic switch for seizing said one end of said trunk line, and

means for releasing said first automatic controlled by the establishment of a connection with said passive contacts for releasing the connection which was extended-from said trunk over the movable contacts, when iaid last connection extends to a busy called 3. In a telephone system, a trunk line, active and passive contacts for one end of said trunk line, means for extending a connection from said trunk line over said active contacts to a called line, and for establishing a busy potential at said passive contacts, means for removing said potential when the called line is busy, means for connecting with said passive contacts, and means controlled by the connection with said passive contacts for releasing the connection from said trunk line if the potential is removed.

4. In a telephone system, a trunk line, active and passive contacts at one end of said trunk line, means for seizing said passive contacts and for thereby disconnecting said active contacts from the trunk line, means for extending a connection over said active contacts from said trunk line to a called line, and for thereby establishing a guarding potential at said passive contacts, and means for removing said guarding potential if the called line is busy.

5. In a telephone system, a trunk line, active and passive contacts at one end of said trunk line, means for seizing said passive contacts and for thereby disconnecting' said active contacts from the trunk line, means for extending a connection over said active contacts from sa1d trunk line to a called line, and for thereby establishing a I a called line over said trunk line, means for seizing said trunk line for extending a connection to said operators position, means controlled by the extension of the connection by the operator for preventing seizure of said trunk line, when the called line is idle, and means for allowing said trunk line to be seized while said connection is estabished by theoperator if the called line is usy, v

7. In a telephone system, a trunk line, active and passive contacts at one end of said trunk line, an automatic switch for seizing -said passive contacts and for thereby disconnecting said active contacts from the trunk line, another automatic switch for extending a connection over said active contacts from said trunk line to a called line, and for thereby establishing a guarding potential at said passive contacts, electromagnetic means in said second switch for removing said guarding potential if the called line is busy, and additional electromagnetic means in said second switch controlled by the seizure of. said passive contacts while the potential is absent for releasing the connection to the called man.

8. In a telephone system, a trunk line, an operators position, an 7 automatic switch controlled. by said operator for'extending a connection to a called line over said trunk line, another automatic switch for seizing said trunk line for extending a connection to said operators position, a relay controlled by the extension of the connection by the operator for preventing seizure of said trunk line, when the called line is idle, and another relay for allowing said trunk line to be seized while said connection is established by the operator if the called line is busy.

Signed by meat Chicago, Cook county,

State of Illinois, this 13th day of March,

" 'JQHN WIOKS. 

